Does LINQ Extension Method Order Impact Performance?

LINQ extension method order: Performance impact analysis

Contrary to initial assumptions, the order in which LINQ extension methods are applied does not significantly affect performance. This conclusion may seem counterintuitive at first glance, since pre-applying a filter (e.g. Where) seems to require processing the entire sequence to obtain the first result.

Explanation

The reason for this unexpected behavior is that LINQ operators are executed immediately upon enumeration. The Where operator does not store all matching elements in memory before getting the first result. Instead, it fetches matching elements on demand. If only the first element is required, only the first matching element is retrieved.

To illustrate this concept, imagine a shuffle game where player 1 has a shuffled deck of cards. Player 2 has a note instructing them to hand the first red card to Player 3. Player 2 does not need to check every card in the deck to find all red cards before handing them to Player 3. They simply start drawing cards until they find a red card, then hand it to player 3.

This analogy applies to the LINQ Where operator. It gets matching elements one at a time, stopping after the first result if only the first result is needed. Therefore, the order in which Where and FirstOrDefault are used does not affect performance, because in both cases, only the first matching element is retrieved.

The above is the detailed content of Does LINQ Extension Method Order Impact Performance?. For more information, please follow other related articles on the PHP Chinese website!